An example of a collimated beam optical system for photographic composing apparatus is taught by S. H. Caldwell U.S. Pat. No. 2,670,665. This device employs a fixed position collimating lens, and a decollimating lens with an angular mirror carried by a carriage. The carriage moves through a composition text line by a stepping drive system. Because a collimated beam is of indefinite length, it may be intercepted by a decollimator at any position. Therefore, an oscillating carriage with a decollimator, with an angular deflector, can be used to step a line of characters along a photosensitive sheet for text composition.
An application Ser. No. 585,610 by Francis S. Szabo is pending before the Patent Office and teaches the use of a variable position lens to produce an aerial image of desired size which is then projected through a collimator lens and decollimated as taught by the prior art. This later copending development concept requires considerably more optical path space than the original shown in U.S. Pat. No. 2,670,665, but provides a very desirable point size change capability.